Fluid circulating and retrieving apparatus for oil wells

ABSTRACT

A RETRIEVING APPARATUS FOR PICKING UP DEBRIS FROM THE BOTTOM OF OIL WELLS COMPRISES A HOLLOW CYLINDRICAL BODY COMMUNICATING AT ITS UPPER END WITH THE LOWER END OF A DRILL PIPE STRING AND TERMINATING AT ITS LOWER END IN AN ENTRANCE OPENING. IN THE PREFERRED EMBODIMENT THERE IS SUPPORTED IN THE BODY A CYLINDRICAL BASKET OF SMALLER DIMENSIONS THAT THE BODY TO DEFINE AN ANNULUS BETWEEN THE EXTERIOR OF THE BASKET AND THE INTERNAL WALLS OF THE BODY ITSELF. THIS ANNULUS COMMUNICATES BETWEEN THE LOWER END OF THE DRILL PIPE STRING AND THE LOWER ENTRANCE OPENING OF THE BODY. A ONE-WAY CATCHER ASSEMBLY IS LOOSELY MOUNTED AT THE LOWER END OF THE BASKET. OIL WELL FLUID IS CIRCULATED DOWN THE OIL WELL BETWEEN THE EXTERIOR WALLS OF THE DRILL PIPE STRING AND APPARATUS AND THE INTERIOR WALLS OF THE WELL AND THENCE UP THROUGH THE ENTRANCE OPENING, CATCHER ASSEMBLY, BASKET AND ANNULUS TO THE INTERIOR OF THE DRILL PIPE STRING. THIS REVERSE CIRCULATION FORCES DEBRIS AND THE LIKE UP THROUGH THE CATCHER ASSEMBLY AND INTO THE BASKET WHERE IT IS HELD BY THE CATCHER ASSEMBLY. WHEN THE BASKET IS FILLED, CIRCULATION CAN BE MAINTAINED THROUGH THE ANNULUS TO THEREBY WASH OUT REMAINING SMALL DEBRIS AND SAND AT THE BOTTOM OF THE WALL. IN OTHER EMBODIMENTS, THE BASKET CAN BE ELIMINATED.

March23, 1971 D. P. HAMMON y 3,512,431 FLUID CIRCULATING AND RETRIEVING APPARATUS FOR OIL AWEIJLS Filed sept. '8, 1969 UnitedStates Patent Olhce 3,572,431 FLUID CIRCULATING AND RETRIEVING APPARATUS FOR OIL WELLS Donald P. Hammon, 2939 Adelita Drive, Hacienda Heights, Calif. 91745 Filed Sept. 8, 1969, Ser. No. 856,107 Int. Cl. E21b 31 08 U.S. Cl. 166-99 3 Claims ABSTRACT OF THE DISCLOSURE A retrieving apparatus for picking up debris from the bottom of oil wells comprises a hollow cylindrical body communicating at its upper end with the lower end of a drill pipe string and terminating at its lower end in an entrance opening. In the preferred embodiment there is supported in the body a cylindrical basket of smaller dimensions than the body to define an annulus between the exterior of the basket and the internal walls of the body itself. This annulus communicates between the lower end of the drill pipe string and the lower entrance opening of the body. A one-way catcher assembly is loosely mounted at the lower end of the basket. Oil well fluid is circulated down the oil well between the exterior walls of the drill pipe string and apparatus and the interior walls of the well and thence up through the entrance opening, catcher assembly, basket and annulus to the interior of the drill pipe string. This reverse circulation forces debris and the like up through the catcher assembly and into the basket where it is held by the catcher assembly. When the basket is filled, circulation can be maintained through the annulus to thereby wash out remaining small debris and sand at the bottom of the wall, In other embodiments, the basket can be eliminated.

This invention relates to oil well tools and ore particularly to an improved fluid circulating and retrieving apparatus for recovering debris and Iwashing out sand and the like in wells.

BACKGROUND OF THE INVENTION During oil well pumping operations wherein a pumping motor is lowered into a completed well casing and fluid pumped through perforations in the casing, various items of junk and debris as well as mud and sand often accumulate at the bottom of the well. One serious source of such debris constitutes sall bands or brackets used to periodically tie electrical cable to pipe string leading from the upper end of the oil well to the pump at the end of the pipe string within the well. As the pipe string is withdrawn the cable is separated at the surface and these small bands or clamps often fall back into the well.

To recover such junk from the well, it is common practice to lower retriever baskets on the end of a pipe string and then circulate fluid down the pipe string and up the well annulus. By providing suitable passages, the fluid can be diverted through the basket to thereby suck up debris at the bottom of the well and trap the same in the basket.

After the basket has been filled, circulation is very poor because of the presence of the debris and thus it is necessary to pull the pipe string and empty the basket. The string must then be lowered into the well and circulation continued to clean out other smaller articles such as sand, mud and the like. This operation is known as Washing out the well.

In addition to the problem `of clogging of the circulation as a consequence of the basket becoming filled with debris, damage to the apparatus itself can result by the 3,572,431 Patented Mar. 23, 1971 debris being picked up. More particularly, the retrieval baskets include a catcher assembly at the lower end through which debris passes and is thus trapped in the basket. In retrieving the debris, the entire apparatus is often rotated by the pipe string to dig into the junk and sand at the bottom of the well. The catcher assembly itself is thus rotated and should there be a large object protruding partway through the assembly, which object itself is stuck and thus stationary, the rotation of the apparatus can damage the assembly requiring replacement as well as preventing operation of the tool.

BRIEF DESCRIPTION OF THE PRESENT INVENTION With the foregoing in mind, it is a primary object of the present invention to provide an improved retrieving apparatus wherein problems encountered with presently available structures relating to clogged circulation and damaged catcher assemblies are overcome.

More particularly, the invention contemplates the provision of a hollow cylindrical body, which, in the preferred embodiment, incorporates an interior basket of smaller dimensions than the body itself. The upper end of the body communicates with the lower end of the pipe string and the lower end of the body terminates in an entrance opening incorporating a catcher assembly means loosely mounted in the opening. The diameter of the basket is less than the interior diameter of the hollow body to define an annulus between the exterior of the basket and the inner 'walls of the hollow body. This annulus communicates with the pipe string at its upper end and the entrance opening at its lower end and provides for free circulation of fluid.

In accord with an important feature of this invention, the circulation of the fluid during the retrieving operation is in a reverse direction; that is, the fluid is pumped down the well between the exterior of the pipe string and apparatus and interior walls of the well and thence into the entrance opening, through the catcher assembly, basket and annulus, to the interior of the pipe string. The fluid is thus brought up through the pipe string to the surface to complete the circulation cycle. It should be noted that with this arrangement full circulation and thus hydraulic force through the apparatus results.

With the foregoing arrangement, and with the catcher assembly loosely mounted such that it can remain stationary while the remaining portion of the apparatus rotates, Various serious problems encountered with prior art devices are avoided. Thus, should the basket become completely filled with debris which would normally block circulation in known types of structures, circulation is still maintained through the annulus between the basket and interior wall of the body. Accordingly, it is possible to not only collect the debris but also to wash out the well of sand and mud during a single trip into the bore hole.

In addition, because of the loose mounting for the catcher assembly, the assembly itself may remain stationary while the apparatus is rotating so that should a large piece of debris jam in the assembly, it -will not be broken.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by referring to a preferred embodiment thereof as illustrated in the accompanying drawings, in which:

FIG. l is a side elevation partly in cross section of an oil well showing a pipe string to which the retrieving apparatus of this invention has been attached for cleaning out debris and other material in the well;

FIG. 2 is a greatly enlarged cross section of the retrieving apparatus of FIG. 1; and,

FIG. 3 is a cross section taken in the direction of the arrows 3 3 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. l, there is shown an oil well lined with casing 11 perforated at 12 for the recovery of oil by suitable pumping apparatus.

As mentioned, such pumping apparatus must be periodically removed and various pieces of junk, debris, and the like tending to accumulate at the bottom of the well such as indicated at 13 removed. In addition, it is often necessary to wash out the well of Sand and mud such as indicated at 14.

Towards the foregoing ends, a retrieval apparatus is lowered on the end of the pipe string indicated at 15. The present invention contemplates an improved retrieval apparatus designated generally by the numeral 16 in FIG. l shown secured to the end of the pipe string 15.

This improved retrieval apparatus is shown in detail with reference to FIG. 2. Basically, the apparatus comprises a hollow cylindrical body 17 having an upper dome shaped section 18 threadedly secured thereto and serving to connect the upper end of the body to the lower end of the pipe string as shown. The lower end of the body in turn connects to a lower section 19 defining a lower entrance opening to the body 17. The extreme lower end of the lower section 19 may be provided with teeth 20 to facilitate penetration of the apparatus into debris, sand, mud, and the like upon rotation of the apparatus by the pipe string 15.

Supported within the hollow body 17 is a cylindrical basket 21 which may have perforated side walls as indicated at 22. A rst internal annular liange 23 is provided on the lower end of the hollow body 17 and may serve to support the lower end of the basket 21 in a coaxial position within the body.

As will be evident from the drawing, the diameter of the basket 21 is smaller than the internal diameter of the hollow body 17 to thereby define an annulus 24 between the exterior Walls of the basket and the interior wall of the body.

The upper end of the basket 21 is closed off as by a screen 25. This screen is held in its shown position by a concentric dome shaped member 26 having a plurality of arch shaped openings 27 and central top opening 28 to provide communication between the upper end of the annulus and the pipe string 15. The lower end of the annulus is in communication with the lower section 19 and its associated entrance opening by suitable holes in the flange 23.

The apparatus is completed by provision of a catcher assembly 29 including fiaps pivoted such as at 30 for one-way movement to the dotted line positions depicted so that debris can pass upwardly through the catcher but is trapped from falling back from the basket through the catcher. As shown, the periphery of the catcher is indicated at 31 and is arranged to be sandwiched within a second annular flange 32 defining a channel 33 formed on the interior of the lower section 19. The sandwiching loosely mounts the catcher structure so that it is free to rotate relative to the body member 17 and lower section 19 but is restrained against appreciable vertical movement.

In the cross section of FIG. 3, it will be noted that the annulus 24 is provided with partitions or angle walls 35 to lend structural strength to the apparatus and properly support the basket in coaxial relationship with the interior wall of the body 17. The catcher structure is shown as comprising four flaps such as indicated at 29 all pivoted for upward swinging movement. The cross-sectional area of the annulus 24, exaggerated in the drawings, is preferably substantially equal to the interior cross-sectional area of the pipe string 15.

4 oPERATroN In operation, the apparatus is secured to the end of a pipe string as by coupling the upper section 18 to the lower end of the pipe string 15 as illustrated in FIGS. 1 and 2. The apparatus is then lowered into the oil Well until the lower section 19 is positioned close to the junk to be retrieved whether it be at the bottom or trapped at an intermediate level. The pipe string may be rotated and simultaneously, reverse fluid circulation is effected by pumping fluid down the well between the exterior walls of the pipe string 15 and apparatus 16 and interior wall of the Well itself. All of the fluid is thus forced up into the entrance opening of the lower section 19 of the apparatus, through. the catcher assembly, the interior of the basket and the annulus 24, the dome shaped structure 26 and thence into the interior of the pipe string 15. This latter circulation is through the apparatus as indicated by the arrows.

The above described circulation of well fluid will force junk and debris and the like through the catcher assembly into the basket wherein the debris is retained. When the basket becomes filled, criculation is still maintained through the annulus 24 so that it is possible to clean out sand, mud, and the like; that is, Wash out the well without having to raise the pipe string and empty the basket. As a result, the retrieval and washing operation can be carried out during a single trip into the bore hole with a considerable savings in time, expense, and labor.

Should any large piece of junk or debris get caught in the catcher assembly 29 while the apparatus is rotating, the catcher will not be broken since the same is fioating in the channel 33 so that the catcher itself can remain stationary while the apparatus continues to rotate. With continued circulation, such caught objects or pieces of junk will eventually work loose and be retrieved in the basket at which time the catcher is free to rotate with the apparatus.

Because of the fact that there is full fluid circulation through the apparatus; that is, all fluid muct pass into the apparatus and up the pipe string, it is possible to eliminate the `basket and simply utilize the body itself to retrieve relatively larger objects such as broken drill cones.

From the foregoing description, it will be evident that the present invention has provided a greatly improved retrieval apparatus wherein full and positive circulation can be continuously realized even though collected junk may completely fill or even clog the holes in the basket and wherein the risks of damaging the apparatus, particularly the catcher assembly, are minimized.

What is claimed is:

1. A fluid circulating and retrieving apparatus for oil wells comprising, in combination:

(a) a hollow cylindrical body;

(b) an upper section connecting the upper end of said body to the lower end of an oil well drill pipe string; (c) a lower section connected to said body to define a lower entrance opening to the interior of said body;

(d) an open ended basket centrally supported within said body of smaller size than said body to define an annulus between the exterior lof said basket and rthe exterior wall of said body, said annulus being in liuid communication with the said upper and lower sections;

(e) an upper screen overlying the upper end of said basket;

(f) a catcher assembly adjacent to said lower entrance opening; and

(g) mounting means coupling said catcher assembly to said body to permit fiuid to pass upwardly therethrough and permit rotation in a horizontal plane while restraining said catcher assembly against vertical movement, whereby said apparatus may be lowered into an oil well and fiuid circulated down said well between the exterior walls of said pipe string and apparatus and the `interior side walls of said pipe string, the lowermost end of said lower section said well, and thence into said lower entrance openincluding teeth to facilitate penetration of said apparatus ing to thereby urge debris and the like into said into any debris and sand in said well when rotating. basket, circulation being maintained through said annulus during and after the time said basket is filled. 5 References Cited 2. Anthappzlaratus azcoring to1 claim in wllich thei UNITED STATES PATENTS cross-sec rona area o sal annu us 1s su stantla y equa to the interior cross-sectional area of said pipe string. CDtllH-a-l 3. An apparatus according to claim 1, in which said 2728599 12/1955 Moor e "2*94-511 mounting means includes an internal annular ange delo 3382925 4/1968 Jennilgg 1`66 L99 lining a channel on the lower inside Wall of said body,

said channel loosely sandwiching the periphery of said JAMES A LEPPTNK Primal-y Examiner catcher assembly so that said catcher assembly is floating and can thus stay rotationally stationary within said U S, C1, XR, apparatus when said apparatus is rotated in said well by 15 166-162 

